Lubricating oil composition



equivalent ratio of 1:2 to 2:1.

United States Patent Ofiice 3,031,401 Patented Apr. 24,

3,031,401 LUBRICATING OIL CGMPOSITION Helen I. Tliayer, Pittsburgh, Pa.,assiguor to Gulf Research & Development Company, Pittsburgh, Pa., acorporation of Delaware No Drawin Filed June 11, 1959, Ser. No. 819,5675 Claims. (Cl. 252-46.7)

This invention relates to lubricating oil compositions having improveddetergency characteristics. More particularly, the invention relates tolubricating compositions containing detergent amounts of certain aminesalts of borylated partially esterifier thiophosphates.

Uncompounded hydrocarbon lubricating oils are frequently objectionablebecause they fail to prevent for- ;mation of rust and because they tendto deposit sludge,

suspension or dispersion in the oil. The use of detergent additivestends to prevent or retard sticking of piston rings, formation ofvarnish-like coatings on the pistons,

cylinder walls and moving parts, and the settling out of sludge in thecrankcase.

I have found that the detergent characteristics of hydrocarbonlubricating oils can be improved by the addition of the reaction productof (a) an oil-soluble primary, secondary or tertiary alkyl (cyclic oropen-chain), alkenyl or alkylol, monoor diamine whose alkyl or alkenylsubstituent-or substituents contain 6 to 22 (preferably 8 to 18 carbonatoms each, such as 3-octadecenylaminopropylamine or tertiaryoctylamine,and '(b) an anhydride prepared by reacting a partially esterifiedthiophosphoric acid containing 1 to 2 organic substituents per moleculeand whose organic substituents are hydrocarbon radicals containing 6 to22 carbon :atoms each, such as 0,0'-diisooctylpheny1 dithiophosphatewith boric acid, boric oxide or an anhydride of boric oxide and analiphatic monocarboxylic acid, preferably a C unsubstituted acid, in theratio of about 0.5 to about 6 moles of partially esterifiedthiophosphoric acid per mole of borylating agent, and wherein the amineto anhydride equivalent ratio is in the range of about 1:2 to 2:1. Thehydrocarbon substituents of the partially esterified thiophosphoric acidcan be alkyl (cyclic or open-chain), alkenyl, aryl, alkaryl or aralkyl.

Normally the detergent characteristics of the oil will be improved bythe use of about 0.1 to 20 percent of the above-indicated reactionproducts. However, other proportions can be used.

The amine derivatives incorporated in the lubricating oils of thisinvention can be prepared in any suitable manner. I prefer, however, toprepare the anhydride of the partially esterified thiophosphate and theborylating agent and thereafter prepare the amine derivative by' addingthat quantity of amine to the borylated thiophosphote ester that willresult in an acid to amine The reaction between the amine and theborylated thiophosphate will procede spontaneously but mild heating maybe desirable to facilitate the reaction. It is to be understood that themethod of preparing these reaction products forms no part of thisinvention. However, it may be mentioned 'that the preferred method ofpreparing these reaction products is disclosed in the copendingapplication of Helen I. Thayer, Serial No. 819,566, filed of even dateherewith. Briefly, the aforementioned application discloses thatreaction products of the kind described herein can be formed by thereaction of a partially esterified -thiophosphoric acid of'the kinddescribed above with boxylic acid, in the range of about 0.5 to about 6moles of thiophosphoric acid ester per mole of borylating agent byrefluxing the reactants in a solvent at the boiling point of the solventfor a period of about 0.5 to about 20 hours. This anhydride product isrecovered and reacted with a suitable amine in the proportion of 0.5 to2 equivalents of anhydride per equivalent of amine, preferably at atemperature of about 40 to 60 C. for about one-half hour or more. Afterthe'reaction is complete, if a solvent was used it is removed and theproduct is recovered.

Examples of the reaction products included in this invention are theamine reaction products of 1 or 2 equivalents of the anhydrides formedfrom boric oxide and ethyl lauryl dithiophosphate (0.5 to 1 molarratio); boric acid and di(2-ethylhexyl) dithiophosphate (1:1 molarratio); anhydride of boric oxide and acetic acid and di(2-ethylhexyl)dithiophosphate (0.25 to 1 molar ratio); boric oxide and dioctyldithiophosphate (1:1 molar ratio); boric-oxide 'and di-p-isooctylphe nyldithiophosphate (0.5 to 1 molar ratio); boric acid and dicyelohexyldithiophosphate (1:1 molar ratio); boric oxide and monooctyldithiophosphate (1:1 molar ratio); boric oxide and d-ibenzyldithiophosphate (0.5 to 1 molar ratio);- boric oxide and di-sperrn oilalcoholester of dithiophosphoric acid (0.5. to. .1 molar ratio); boric'oxide and diphenyl dithiophosphate (0.5 to 1 molar ratio); and 1 or 2equivalents of amines such as any of the following: 2-ethylhexy1amine,cyclohexylamine, dicyclohexylamine, trioctylamine, o ctylamine,decylamine, dodecylamine, N-octadecenyl ethylene diamine,1,1,3,3-tetramethylbutylamine, and those monoand diamines where therespective nitrogen substituents are mixed alkyl and alkenyl groupsobtained from naturally occurring fats and oils, e.g., tallow, soybeanoil, coconut oil and the like. In such instances the aliphaticN-substituents will be monovalent straight chain hydrocarbon radicalscontaining an even number of carbon atoms from 8 to 22. Examples of suchmixtures are: 3 -tallowaminopropylamine, 3-soyaaminopropylaamine,3-coco-arninopropylamine, cocoamine, etc.

The amine reaction products of the borylated partially esterifiedthiophosphates disclosed herein are useful when incorporated in mineraloils in minor proportions sufiicient to confer detergent properties onthe composition. For example, satisfactory results will be obtained bythe use of about 0.1 to 20 percent of the additive based on the weightof the lubricating oil. Especially efiective results normally will beobtained with the use of about 0.5 to about 10 percent by weight in thelubricating oil disclosed herein and this constitutes the preferredrange of proportions.

The amine reaction products of the borylated partially esterifiedthiophosphates disclosed herein may be incorporated in lubricating'oilsin'any suitable manner; Thus, the compounds may be added per se directlyto the lubricating oils or in the form of concentrates. Suitableconcentrates containing the addition agents of this invention comprise,for example, lubricating oil solutions or dispersions containing about10 to about percent by weight and preferably 25 to 50 percent by weightactive ingredients.

The following examples illustrate various methods of preparing myadditives and improved compositions containing the same:

EXAMPLE 1 Borylated 0,0-di(p-isooctylphenyl) dithiophosphoric acid wasprepared by heating 126 grams (0.25 mole) of di-(p-isooctylphenyl)dithiophosphoric acid with 15 grams (0.22 mole) of boric oxide in thepresence of benzene.

Heating was continued for 17 hours at temperatures of 80 to 100 C. andthe solution was filtered to remove the unreacted boric oxide. The aminereaction product was prepared by adding 88 grams (0.44 equivalent) ofthe commercial 3-tallow-aminopropylamine which is a mixture of alkylandalkenylaminopropylamines having from 14 to 18 carbon atoms, whose aminosubstituents are mixed groups derived from tallow fatty acids,predominantly 3-octadecenyl groups, to 151 grams (0.22 equivalent) ofborylated phosphate ester in benzene. The solution was heated to 30 to60 C. for 40 minutes. The benzene was removed by distillation at itsboiling point and the product recovered. The analysis was as follows:

Percent Boron 0.5 3 Phosphorus 3 .5 3 Sulfur 3.88

A lubricating oil composition was prepared by adding 3 percent of thisproduct to a commercial lubricating oil, a typical sample of which hadthe following inspection.

EXAMPLE 2 In another preparation of the 0,0'-di(p-isooctylphenyl)dithiophosphoric acid compound was synthesized as follows:

A charge of 1 mole (206.3 grams) of p-isooctylphenol was added to aflask equipped with a stirrer and a reflux condenser. The phenol washeated to 115 C. and phosphorus pentasulfide (P 8 in the amount of 55.5grams (0.125 mole) was added slowly enough to keep the temperature inthe range of 130 to 145 C. The solution was stirred vigorously for 3hours. The crude product was filtered hot through glass wool. One-tenthof an equivalent (61.7 grams) of crude diisooctylphenyl dithiophosphoricacid in 125 milliliters of benzene and 7 grams (0.1 mole) of boric oxidewere heated under reflux at the boiling point of benzene for 22.5 hours.The solution was then cooled, filtered and the solvent removed bydistillation at its boiling point. The product analysis was Neutralequivalent is defined as that amount of material in grams which willfurnish one mole of hydrogen ion or will react with one equivalent(56.10 grams) of potassium hydroxide.

A charge of 26.6 grams (0.064 equivalent) of this prod- -uct wasdissolved in 50 milliliters of hexane and placed in a flask equippedwith a stirrer. The amine, 25.6 grams (0.13 equivalent) of 3- tallow-aminopropylamine as defined above, was dissolved in 25 milliliters ofhexane and added to the product of the above-described reaction withvigorous stirring. After the reaction was complete, the solution wascooled, filtered and the solvent removed under vacuum. An oil solutionof the product gave an alkaline test. The product analysis was asfollows:

Percent Sulfur 2.95 Boron 0.62

A lubricating oil composition was prepared by adding 1 percent of thisproduct to the commercial lubricating oil of Example 1.

EXAMPLE 3 The same compound was prepared using the method T I of Example2 except that the solvent used was benzene and the duration of theborylation step was 17 hours. The analysis of the compound afterneutralization with amine was as follows:

Percent Boron 0.46 Phosphorus 3.30 Sulfur 4.01

A lubricating oil composition Was prepared by adding 3 percent of thisproduct to the commercial lubricating oil of Example 1.

EXAMPLE 4 Percent Boron 0.48 Phosphorus 3.14 Sulfur 5.04

A lubricating oil composition was prepared by adding 3 percent of thisproduct to the commercial oil of Example 1.

The detergent lubricating oil compositions described in the foregoingspecific embodiments are illustrative only, and the invention is notlimited thereto. Satisfactory results can be obtained by thesubstitution in the foregoing examples of other amines disclosed hereinand other borylated partially esterified thiophosphates disclosed hereinin the same or equivalent proportions.

The usefulness of the reaction products of the amines and borylatedpartially esterified thiophosphates has been demonstrated by means of adetergency bench-test procedure. This test apparatus and procedureevaluate the resistance of oil to oxidation and high temperaturedeterioration by splashing the test oil against a heated metal panelmounted on the test apparatus. The weight and character of the paneldeposit is used in evaluating the utility of the test oil in automobileengines. The emphasis has been placed on the detergency or depositpreventing characteristics of the test oil oxidized by air during thetest in addition to qualitative observations of the oxidation stability.

The apparatus consists of a reservoir mounted on legs. An oil levelingtube is welded under the bottom of the unit and an oil splasher(consisting of a series of stainless steel wires mounted on a shaft toform a cylindrical brush) is rotatably mounted in the unit. Heat to theoil reservoir is supplied by a strip heater attached to the bottom ofthe oil reservoir. In operation, test oil is thrown against theunderside of an electrically heated test panel positioned in the centerof the oil reservoir cover. In a typical test, 225 milliliters of testoil is poured into the oil reservoir and pro-heated to about to F. Theoil level device is filled and positioned to maintain the oil at theinitial oil level. The test panel is polished and tared, and the heatercontrol thermocouple is inserted in the panel positioned on the oilreservoir cover. During 5 operation air is drawn through the system at arate of about liters per hour. The splasher is turned on after the testpanel reaches a temperature of 500 F. At this point the oil reservoirheater is turned off and the splasher speed is adjusted to 1000 r.p.m.The test is continued for a period of 8 hours.

At the end of the test the panel is removed and allowed to drain andcool. The oil temperature is checked and the apparatus disconnected fromthe air system and drained. The discharge oil is observed for color,odor, sludge or other evidences of deterioration. After cooling the testpanel is washed free from oil, allowed to dry and is weighed. The weightgain of the panel in milligrams is recorded. The visual rating isobtained by scoring the appearance of the deposit against the scalewhich encompasses varying degrees of deposit from rough black coke tovery light lacquer. Experience has shown good reproducibility can beobtained both in test panel appearance and in weight changes.

The unusual effectiveness of the reaction products of the amines and theborylated partially esterified'thiophosphates is demonstrated by thedata presented in Table I below:

Lubricating oil composition of Example 2 These data show that the aminesalts of borylated dithiophosphates of the kind included by thisinvention significantly decreased the amount of sludge deposited fromthe oil and that these additives have effective detergent properties.Thus, the addition of only 1 percent of the composition to thelubricating oil decreased the deposits from more than 100 milligrams toabout 6 milligrams. The slight increase in the weight of the depositswhen 3 percent of the compound of Example 1 was employed was probablydue to slight differences in the composition of the reaction productprepared by the method of Example 1.

It is also contemplated that the addition agents Whose use is covered bythis invention also possess bearing corrosion inhibiting properties.

The lubricating compositions of my invention can contain minor amountsof addition salts other than amine salts of bolyrated partiallyesterified thiophosphates. Thus, for example, it is particularlyadvantageous in many instances to add an anti-foam agent to thelubricating composition. Other addition agents normally added tolubricating oils for a specific purpose, such as an antioxidant, pourpoint depressant, corrosion inhibitor, viscosity index improver,oiliness and extreme pressure agent and the like, can be employedwithout adversely aflecting the improved detergent characteristics ofthe lubricating compositions of this invention.

While my invention is described with reference to various specificexamples and embodiments, it will be understood that the invention isnot limited to such examples and embodiments may be variously practicedwithin the scope of the claims hereinafter made.

I claim:

1. A lubricating composition comprising a major amount of a hydrocarbonlubricating oil and a minor amount, sufficient to improve the detergentcharacteristics of said oil, of a reaction product of (a) a memberselected from the group consisting of primary, secondary and tertiaryalkyl, alkenyl and alkylol, monoand diamines whose substituents eachcontain 6 to 22 carbon atoms, and (b) an anhydride prepared by reactinga partially esterified thiophosphoric acid containing 1 to 2 organicsubstituents per molecule, whose substituents are selected from a groupconsisting of alkyl, cycloalkyl, alkenyl, aryl, alkaryl, and aralkylhydrocarbon radicals containing 6 to 22 carbon atoms each, with aborylating agent selected from the group consisting of boric acid, boricoxide, and an anhydride of boric oxide and an aliphatic monocarboxylicacid, in the ratio of about 0.5 to about 6 moles of partially esterifiedthiophosphoric acid per mole of borylating agent, and wherein the amineto anhydride equivalent ratio is in the range of about 1:2 to 2:1.

2. The lubricating composition of claim 1 where said minor amount isabout 0.1 to 20 percent by weight of said oil.

3. The lubricating composition of claim 1 where said minor amount isabout 0.5 to 10 percent by weight of said oil.

4. The lubricating composition of claim 1 where said amine is3-tallow-aminopropylamine, said partially esterified thiophosphoric acidis 0,0'-di(p-isooctylphenyl) dithiophosphoric acid, said borylatingagent is boric oxide, and the molar ratio of partially esterifiedthiophosphoric acid to borylating agent is about 1:1, and the anhydrideto amine equivalent ratio is about 1:2.

5. The lubricating composition of claim 1 where said amino is3"tallow"-aminopropylamine, said partially esterified thiophosphoricacid is 0,0'-di(p-isooctylphenyl) dithiophosphoric acid, said borylatingagent is boric acid, and the molar ratio of borylating agent topartially esterified dithiophosphoric acid is about 1:1, and theanhydride to amine equivalent ratio is about 1:2.

References Cited in the file of this patent UNITED STATES PATENTS

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF A HYDROCARBONLUBRICATING OIL AND A MINOR AMOUNT, SUFFICIENT TO IMPROVE THE DETERGENTCHARACTERISTICS OF SAID OIL, OF A REACTION PRODUCT OF (A) A MEMBERSELECTED FROM THE GROUP CONSISTING OF PRIMARY, SECONDARY AND TERTIARYALKYL, ALKENYL AND ALKYLOL, MONO- AND DIAMINES WHOSE SUBSTITUENTS EACHCONTAIN 6 TO 22 CARBON ATOMS, AND (B) AN ANHYDRIDE PREPARED BY REACTINGA PARTIALLY ESTERIFIED THIOPHOSPHORIC ACID CONTAINING 1 TO 2 ORGANICSUBSTITUENTS PER MOLECULE, WHOSE SUBSTITUENTS ARE SELECTED FROM A GROUPCONSISTING OF ALKYL, CYCLOALKYL, ALKENYL, ARYL, ALKARYL, AND ARALKYLHYDROCARBON RADICALS CONTAINING 6 TO 22 CARBON ATOMS EACH, WITH ABORYLATING AGENT SELECTED FROM THE GROUP CONSISTING OF BORIC ACID, BORICOXIDE, AND AN ANHYDRIDE OF BORIC OXIDE AND AN ALIPHATIC MONOCARBOXYLICACID, IN THE RATIO OF ABOUT 0.5 TO ABOUT 6 MOLES OF PARTIALLY ESTERIFIEDTHIOPHOSPHORIC ACID PER MOLE OF BORYLATING AGENT, AND WHEREIN THE AMINETO ANHYDRIDE EQUIVALENT RATIO IS IN THE RANGE OF ABOUT 1:2 TO 2:1.